JP3784307B2 - Electric power steering system for cargo handling vehicles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric power steering apparatus for a cargo handling vehicle having an openable / closable safety guard for protecting an operator.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is an order picking truck as a cargo handling vehicle having an openable / closable safety guard that protects an operator on a driver's cab, and an electric power steering device in this order picking truck includes, for example, a steering handle and a steering operated by an operator. A mechanism that does not have a mechanical connection structure with a steering mechanism including a free steering wheel or the like is employed, and is configured as shown in FIG.
[0003]
That is, as shown in FIG. 5, the operation speed when the steering handle provided on the vehicle body of the order picking truck is rotated is detected by the operation speed sensor 1 composed of an encoder or the like, and the power steering motor 2 The motor rotation speed is detected by a motor rotation speed sensor 3 composed of an encoder or the like, and the target steering speed calculator 4 derives the target steering speed from the operation speed of the steering handle detected by the operation speed sensor 1 by calculation. At this time, since the steering handle operating speed and the target steering speed are in a proportional relationship, the target steering speed can be derived by multiplying the detected steering handle operating speed by a certain constant.
[0004]
Then, the difference between the target steering speed and the motor rotational speed detected by the motor rotational speed sensor 3 is calculated by the adder / subtractor 5, and this difference is given to the motor driver 6 comprising a chopper circuit or an inverter circuit. Thus, the output of the power steering motor 2 is controlled. Thus, the motor rotation speed by the motor rotation speed sensor 3 is controlled so as to coincide with the target steering speed, and the steering of the steering wheel is controlled according to the rotation operation of the steering handle. At this time, control by the motor driver 6 is performed so that the power steering motor 2 rotates in the operation direction of the steering handle by the operation speed sensor 1.
[0005]
[Problems to be solved by the invention]
However, in the case of an order picking truck, the driver's cab portion on which the operator is boarded moves up and down, and the steering wheel is arranged at the lower part of the vehicle body so that it is particularly difficult for the operator's eyes to see. The device has a structure that allows the steering handle to rotate indefinitely without any end. For example, when the vehicle is picked up in a stationary state and then travels again, or when the operator gets out of the vehicle and re-boards. Sometimes, the operator cannot figure out which direction the steered wheel is facing.
[0006]
Therefore, conventionally, the vehicle is driven at an extremely low speed, and the direction of the steering wheel is confirmed based on the traveling direction. However, since the work of confirming the direction of the steering wheel is necessarily required, the work efficiency is improved. There was a problem of causing a decrease in Furthermore, the operator may accidentally hit the vehicle against a wall or the like during such confirmation work, which is not preferable for safety.
[0007]
Such a phenomenon is not limited to an order picking truck, and is a problem that can occur in common in a cargo handling vehicle having a structure in which steering wheels are difficult to see from the outside. In particular, a steering mechanism including a steering handle and steering wheels, etc. This is conspicuous in the case where no mechanical connection structure is provided.
[0008]
Therefore, an object of the present invention is to eliminate the work of confirming the direction of the steered wheels and improve work efficiency.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a cargo handling vehicle having an openable safety guard for protecting an operator on a cab, and detecting the rotation of a steering handle. In an electric power steering apparatus for a cargo handling vehicle that controls a power steering motor based on a value to steer a steering mechanism, a steering angle detecting means for detecting a steering angle of the steering mechanism and a state of the safety guard are detected. Safety guard detection means and the power so that the steering angle detected by the steering angle detection means reaches a value corresponding to a straight traveling state of the vehicle when the safety guard detection means detects opening of the safety guard. And a control means for driving and controlling the steering motor.
[0010]
According to such a configuration, when opening of the safety guard is detected by the safety guard detection means, it can be determined that the operator is performing an operation other than the traveling operation or is away from the cab. In such a case, since the power steering motor is driven and controlled by the control means so that the steering angle detected by the steering angle detection means reaches a value corresponding to the straight traveling state, the operator tries to resume the traveling operation. When this is done, it is not necessary to check which direction of the steered wheels, and the next traveling operation can be started from a state in which the steered wheels are directed straight. Therefore, the conventional operation of confirming the direction of the steered wheels is not required, so that the work efficiency can be improved and the safety of the vehicle can be improved by eliminating the possibility of hitting the vehicle.
[0011]
At this time, the safety guard detection means may be configured by a limit switch that is turned on and off in conjunction with the opening and closing of the safety guard. In this case, the safety guard is any one that is arranged to protect the worker. It may be in such a form.
[0012]
The invention according to claim 2 is provided with a timer that counts a predetermined time after the safety guard detecting means detects the opening of the safety guard, and the control means includes the safety guard detecting means by the safety guard detecting means. If the detection of the release of the vehicle continues for the predetermined time, the power steering motor is driven and controlled so that the steering angle detected by the steering angle detection means reaches a value corresponding to the straight traveling state of the vehicle. It is a feature.
[0013]
According to such a configuration, if the detection of the opening of the safety guard by the safety guard detection means continues for a predetermined time counted by the timer, the operator is performing an operation other than the traveling operation, or the cab There is no mistake even if it is determined that the vehicle is away from the vehicle. Therefore, there is no problem even if the steering wheel is steered in a straight direction.
[0014]
According to a third aspect of the present invention, the control means is configured so that the steering angle reaches a value corresponding to a straight traveling state of the vehicle when the safety guard detecting means detects the closure of the safety guard. It is characterized in that the process for driving and controlling the power steering motor is stopped.
[0015]
According to such a configuration, by returning the safety guard from the open state to the closed state, the process of returning the steered wheels to the state in which the steered wheels are directed straight is stopped, so that the steered wheels can be steered immediately. .
[0016]
DETAILED DESCRIPTION OF THE INVENTION
One embodiment when the present invention is applied to an order picking truck which is a cargo handling vehicle will be described with reference to FIGS. 1 and 2 are perspective views when the order picking track according to the embodiment of the present invention is viewed from different directions, FIG. 3 is a block diagram of the control system, and FIG. 4 is a flowchart for explaining the operation.
[0017]
As shown in FIGS. 1 and 2, the order picking truck 10 according to the present embodiment is mainly composed of a vehicle main body 11, a mast device 12 erected substantially at the center of the vehicle main body 11, and an operator on the mast device 12. A cab 13 provided at the rear of the vehicle main body 11 so as to be movable up and down along the device 12, and a pair of forks 14 attached to the lower portion of the cab 13.
[0018]
The driver's cab 13 includes a floor portion 131 on which an operator gets on, a pair of support columns 132 erected on the left and right front ends of the floor portion 131, and a protective head guard 133 for the operator fixed to the upper ends of both support columns 132. And a U-shaped safety guard 134 whose front ends are pivotally supported at a position slightly above the center of both struts 132, and the front end portions of the struts 132 are pivotally supported substantially at the center. A pair of left and right lateral guards 135 are provided.
[0019]
Although not shown in FIGS. 1 and 2, the safety guard 134 is urged upward by springs embedded in both struts 132, and the urging force of the springs causes the rear end of the safety guard 134 to move. The safety guard 134 can be opened simply by lifting up. And in the open state of the safety guard 134, it is set as the state which cannot drive | work and handle for safety ensuring. On the other hand, when the rear end portion of the safety guard 134 is pulled downward against the urging force of the spring, the safety guard 134 is held (locked) in a closed state by a lock mechanism (not shown) so that traveling and cargo handling are possible. Return to the state.
[0020]
At this time, although not shown in FIGS. 1 and 2, the safety guard switch composed of a limit switch as a safety guard detecting means for detecting the open / closed state of the safety guard 134 is provided for both or either of the columns 132. Attached to one side. As a result, when the front end of the safety guard 134 is rotated as the safety guard 134 is opened and closed, the safety guard switch is turned off when the safety guard 134 is opened and turned on when the safety guard 134 is closed. Opening / closing of the safety guard 134 is detected.
[0021]
By the way, when the safety guard 134 is viewed from the side, the latter half is bent downward, and the transverse beam 134A at the rear end of the safety guard 134 in the closed state is located just at the waist of the operator. Together with the lateral guard 135, the operator is prevented from dropping from the cab 13.
[0022]
As shown in FIG. 1, an operation unit 16 for operating the order picking truck 10 is provided at a substantially central portion of the front surface of the cab 13. The operation unit 16 includes a steering handle 161, an elevating operation. A plurality of switches 162, an accelerator lever 163 that can be rotated bidirectionally from a neutral state, a display that displays the state of each part, and the like are disposed. Furthermore, a metal net 17 is attached to the upper half of the cab 13 in order to ensure a forward view. In FIG. 1, 18 is a pair of left and right driven wheels disposed at the lower rear end of the floor portion 131 of the cab 13 and 20 is a brake pedal. When an operator steps on the brake pedal 20, the brake is released. It becomes possible to run, and if the stepping is stopped, the brake is applied and the vehicle is stopped.
[0023]
Further, as shown in FIG. 2, in addition to the traveling device 22, the hydraulic device 24, the control device 26, a battery not shown in FIG. 2 is accommodated in the accommodating portion provided at the front portion of the vehicle body 11. Has been. The traveling device 22 includes a traveling motor 221, a speed reduction mechanism 222 including several gears that transmit the rotation of the traveling motor 221, and the rotation of the traveling motor 221 is transmitted via the speed reduction mechanism 222. And a steered wheel 223 to be driven. The hydraulic device 24 includes a hydraulic motor 241 and an electromagnetic valve 242, and the control device 26 includes a control circuit that controls each part.
[0024]
The rotation of the power steering motor not shown in FIG. 2 is transmitted to the steering wheel 223 by the steering mechanism, and the steering wheel 223 is steered. At this time, in the order picking truck 10, there is no mechanical connection structure between the steering handle 161 and the steering mechanism, and the steering wheel 223 is steered by an electric power steering device as described below.
[0025]
That is, as shown in FIG. 3, an operation speed sensor 31 including an encoder for detecting an operation speed when the steering handle 161 of the order picking truck 10 is rotated is provided on the vehicle main body 11, and a power steering motor. A steering angle sensor 33 including a potentiometer that detects the steering angle of the steering wheel 223 steered by the steering wheel 223 is provided in the vehicle body 11.
[0026]
Then, the target steering speed calculation unit 34 derives the target steering speed from the operation speed of the steering handle 161 detected by the operation speed sensor 31. Here, since the operation speed of the steering handle 161 and the target steering speed are in a proportional relationship, the target steering speed is derived by multiplying the operation speed detected by the operation speed sensor 31 by a certain constant. Further, the relationship between the operation speed of the steering handle 161 and the target steering speed is tabulated in advance and stored in a storage means such as a memory provided in the target steering speed calculation unit 34 and detected by the operation speed sensor 31. The target steering speed corresponding to the operation speed may be read out.
[0027]
Further, the steering angle detected by the steering angle sensor 33 is differentiated by the motor rotation speed calculation unit 35, the rotation speed of the power steering motor 32 is calculated, and the calculated motor rotation speed and the target steering speed calculation unit 34 are calculated. The difference from the target steering speed calculated by is calculated by the adder / subtractor 36, and this difference is given to the motor driver 37 comprising a chopper circuit or an inverter circuit. The motor driver 37 controls the output of the power steering motor 32, Thus, the motor rotation speed by the motor rotation speed calculation unit 35 is controlled so as to coincide with the target steering speed, and the steering of the steering wheel 223 is controlled according to the rotation operation of the steering handle 161. At this time, the rotation direction of the steering handle 161 is also detected by the operation speed sensor 31, and control by the motor driver 37 is performed so that the power steering motor 32 rotates in the detected rotation direction.
[0028]
By the way, as shown in FIG. 3, when the safety guard switch 41 is turned off by opening the safety guard 134, the timer 42 that counts a predetermined time (for example, 180 seconds) starts counting, and this timer If the safety guard switch 41 is kept off, that is, if the safety guard 134 is kept open for 180 seconds (predetermined time) counted by 42, the steering angle detected by the steering angle sensor 33 is the vehicle. The motor driver 37 is controlled on the basis of the output of the target steering speed calculation unit 34 so as to reach a value (for example, 0 °) corresponding to the straight traveling state of the vehicle, and the power steering motor 32 is driven to automatically steer the wheels. The direction of 223 is steered to the straight traveling state of the vehicle.
[0029]
At this time, if the safety guard 134 is kept open for 180 seconds (predetermined time) counted by the timer 42, when the timer 42 count ends, the target steering speed calculation unit 34 sends the motor driver. The automatic steering control signal continues to be output until the steering angle detected by the steering angle sensor 33 input to the target steering speed calculator 34 becomes zero. Based on this automatic steering control signal, the motor driver 37 drives the power steering motor 32 in a predetermined direction so as to obtain a constant output, and the steering wheel 223 is steered in a straight traveling state.
[0030]
On the other hand, when the steering handle 161 is operated during the automatic steering process operation of the steering wheel 223 and the output of the operation speed sensor 31 is not zero, or the safety guard 134 is closed and the safety guard switch 41 is closed. When is turned on, the automatic steering process of the steering wheel 223 described above is immediately stopped, and a transition is made to a normal state in which the steering wheel 223 can be steered based on the operation of the steering handle 161. The target steering speed calculation unit 34 and the motor driver 37 that control the automatic steering process and the automatic steering process are equivalent to the control means in the present invention.
[0031]
Next, the operation will be described with reference to the flowchart of FIG. As shown in FIG. 4, it is determined whether or not the operation speed of the steering handle 161 by the operation speed sensor 31 is 0 (S1). If this determination result is YES, whether or not the safety guard switch 41 is off. If this determination result is YES, it can be determined that the safety guard 223 is open, and the timer 42 starts counting.
[0032]
Then, it is determined whether or not the count value of the timer 42 is 180 seconds (predetermined time) or more (S3). If the determination result is NO, the timer 42 counts up (S4), and the steering handle In order to perform normal steering based on the operation of 161, the power steering motor 32 is controlled (S5), and then the operation ends.
[0033]
On the other hand, if the determination result in step S3 is YES, the safety guard 134 is kept open for 180 seconds (predetermined time) counted by the timer 42. It is possible to determine that the person is away from the driver's cab 13, and the power steering motor is executed until the automatic steering process is executed to bring the steering wheel 223 straight, and the detected steering angle by the steering angle sensor 33 becomes zero. 32 is controlled to automatically steer the direction of the steered wheels 223 to the straight traveling state of the vehicle (S6), and then the operation ends.
[0034]
By the way, if the determination results in the above-described steps S1 and S2 are NO, the count of the timer 42 is cleared (S7), and then the process proceeds to the above-described step S5 to perform normal steering based on the operation of the handle 161. Control processing of the power steering motor 32 is executed.
[0035]
In this way, the safety guard 134 is detected to be released when the safety guard switch 41 is turned off, and the detection of opening of the safety guard 134 due to the safety guard switch 41 being turned off continues for the count time of the timer 42 (180 seconds). For example, it can be determined that the worker is performing an operation other than picking work or other traveling operation, or is leaving the cab for getting off, and is detected by the steering angle sensor 33 in such a case. The power steering motor 32 is controlled so that the steering angle reaches a value corresponding to the straight traveling state of the vehicle, and the steering wheel 223 is automatically steered to the straight traveling state.
[0036]
Therefore, according to the above-described embodiment, when the operator tries to resume the traveling operation, it is not necessary to confirm which direction the steering wheel 223 is, and the steering wheel 223 is directed straight. The next traveling operation can be started from the state. Therefore, the conventional operation of confirming the direction of the steered wheels 223 is not required, the work efficiency can be improved, and safety can be improved without fear of hitting the vehicle.
[0037]
If the steering wheel 161 is operated or the safety guard 134 is closed and the safety guard switch 41 is turned on during the automatic steering process of the steering wheel 223 to the straight traveling state, the steering wheel 223 is brought into the straight traveling state. Since the automatic steering process is stopped and the steering wheel 223 is shifted to a state in which the steering wheel 223 can be steered based on the operation of the steering handle 161, the operator can easily perform the automatic steering process to bring the steering wheel 223 to the straight traveling state at any time. Can be canceled.
[0038]
In the above-described embodiment, if the open state continues for the counting time (180 seconds) by the timer 42 after the opening of the safety guard 134 is detected, the power steering motor 32 is forcibly controlled. Although the case where the steering wheel 223 is automatically steered to the straight traveling direction has been described, the count time of the timer 42 in this case is not particularly limited to the above-described 180 seconds.
[0039]
In addition, it is not always necessary to provide such a timer 42. When the opening of the safety guard 134 is detected, the power steering motor 32 is immediately forcibly controlled so that the direction of the steered wheels 223 is automatically controlled to go straight. You may make it face.
[0040]
Further, in the above-described embodiment, the case where the safety guard detection means is the safety guard switch 41 including the limit switch that is turned on / off in conjunction with the opening / closing of the safety guard 134 has been described. The switch is not limited to a switch and may be any device that can detect the opening and closing of the safety guard regardless of the contact type or the non-contact type.
[0041]
Further, the safety guard 134 is not limited to the above-described flip-up type, and may be, for example, a fence-like one surrounding the cab 13 as long as it is disposed on the cab 13 so as to protect the operator. The part or the front part may be openable and closable.
[0042]
Furthermore, in the above-described embodiment, the case where the present invention is applied to the order picking truck 10 has been described. However, the scope of the present invention is not limited to this, and other cargo handling vehicles may include a safety guard. The present invention can be applied to what is provided, especially when the direction of the steered wheel is difficult to see from the outside or when the steering wheel and the steering mechanism do not have a mechanical connection structure. It is effective. Also, a safety guard and a mechanical connection structure between the steering handle and the steering mechanism can be applied.
[0043]
The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.
[0044]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the safety guard detecting means detects the opening of the safety guard, the operator is performing an operation other than the traveling operation or separated from the cab. In such a case, the control means controls the power steering motor so that the steering angle detected by the steering angle detection means reaches a value corresponding to the straight traveling state. When the vehicle tries to resume the traveling operation, it is not necessary to confirm which direction the steering wheel is, and the next traveling operation can be started from a state in which the steering wheel is directed straight. Therefore, the conventional operation of confirming the direction of the steered wheels is not required, so that the work efficiency can be improved and the safety of the vehicle can be improved by eliminating the possibility of hitting the vehicle around.
[0045]
According to the second aspect of the present invention, when the detection of the opening of the safety guard by the safety guard detecting means continues for a predetermined time counted by the timer, the operator performs an operation other than the traveling operation. There is no mistake even if it is determined that the steering wheel is away from the cab, so there is no problem even if the steered wheels are automatically returned to the straight direction, and reliable control can be performed. It becomes possible.
[0046]
According to the third aspect of the present invention, the process of automatically returning the steered wheels to the straight direction is stopped by returning the safety guard from the open state to the closed state. It becomes possible to steer the steered wheel with the handle.
[Brief description of the drawings]
FIG. 1 is a perspective view of an order picking track according to an embodiment of the present invention viewed obliquely from the rear.
FIG. 2 is a perspective view of an order picking track according to an embodiment of the present invention as viewed obliquely from the front.
FIG. 3 is a block diagram of a control system in one embodiment of the present invention.
FIG. 4 is a flowchart for explaining the operation of the embodiment of the present invention.
FIG. 5 is a block diagram of a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Order picking truck 11 Vehicle main body 13 Driver's cab 31 Operation speed sensor 32 Power steering motor 33 Steering angle sensor (steering angle detection means)
34 Target steering speed calculation unit (control means)
37 Motor driver (control means)
41 Safety guard switch (safety guard detection means)
42 Timer 134 Safety Guard 161 Steering Handle 223 Steering Wheel

Claims (3)

A cargo handling vehicle having an openable safety guard for protecting an operator on a driver's cab, which detects rotation of a steering handle and controls a power steering motor based on the detected value to steer a steering mechanism. In an electric power steering device for a vehicle,
Steering angle detection means for detecting the steering angle of the steering mechanism;
Safety guard detecting means for detecting the state of the safety guard;
Drive control of the power steering motor so that the steering angle detected by the steering angle detection means reaches a value corresponding to the straight traveling state of the vehicle when the safety guard detection means detects the opening of the safety guard. And an electric power steering device for a cargo handling vehicle. A timer that counts a predetermined time after the safety guard detection means detects the opening of the safety guard;
If the detection of the opening of the safety guard by the safety guard detection means continues for the predetermined time, the control means sets the steering angle detected by the steering angle detection means to a value corresponding to the straight traveling state of the vehicle. The electric power steering apparatus for a cargo handling vehicle according to claim 1, wherein the power steering motor is driven and controlled to reach the load steering vehicle. The control means performs a process for driving and controlling the power steering motor so that the steering angle reaches a value corresponding to a straight traveling state of the vehicle when the safety guard detecting means detects the closure of the safety guard. The electric power steering device for a cargo handling vehicle according to claim 1 or 2, wherein the electric power steering device is stopped.

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